The present invention relates generally to an apparatus for detecting objects adjacent open elevator doors and, in particular, to a light barrier for automatically controlling elevator car doors in response to detected objects.
The U.S. Pat. No. 4,452,009 (European Patent Specification 0 081 110) shows a light barrier having light emitting transmitters slidably mounted in grooves in the elevator car door sill and coupled to the elevator car doors for movement adjacent the leading edges of the doors. Light receivers are mounted on the upper edges of the car doors for synchronous movement with the light transmitters. The light transmitters generate vertical light beams to the light receivers for detecting objects near the door edge. The light receivers are connected to the door control to control the automatic actuation of the car doors which reopen upon detection of an object. An advantage of detection limited to the door edge is that the door control is not unnecessarily interrupted by objects far away from the door edge. However, a disadvantage is that such a light barrier will not detect objects spaced from the edges of the doors such as a person in the hallway about to enter the elevator car.